# RapidJSON Features ## General * Cross-platform * Compilers: Visual Studio, gcc, clang, etc. * Architectures: x86, x64, ARM, etc. * Operating systems: Windows, Mac OS X, Linux, iOS, Android, etc. * Easy installation * Header files only library. Just copy the headers to your project. * Self-contained, minimal dependences * No STL, BOOST, etc. * Only included `<cstdio>`, `<cstdlib>`, `<cstring>`, `<inttypes.h>`, `<new>`, `<stdint.h>`. * Without C++ exception, RTTI * High performance * Use template and inline functions to reduce function call overheads. * Optional SSE2/SSE4.1 support. ## Standard compliance * RapidJSON should be fully RFC4627/ECMA-404 compliance. * Support unicode surrogate. * Support null character (`"\u0000"`) * For example, `["Hello\u0000World"]` can be parsed and handled gracefully. There is API for getting/setting lengths of string. ## Unicode * Support UTF-8, UTF-16, UTF-32 encodings, including little endian and big endian. * These encodings are used in input/output streams and in-memory representation. * Support automatic detection of encodings in input stream. * Support transcoding between encodings internally. * For example, you can read a UTF-8 file and let RapidJSON transcode the JSON strings into UTF-16 in the DOM. * Support encoding validation internally. * For example, you can read a UTF-8 file, and let RapidJSON check whether all JSON strings are valid UTF-8 byte sequence. * Support custom character types. * By default the character types are `char` for UTF8, `wchar_t` for UTF16, `uint32_t` for UTF32. * Support custom encodings. ## API styles * SAX (Simple API for XML) style API * Similar to [SAX](http://en.wikipedia.org/wiki/Simple_API_for_XML), RapidJSON provides a event sequential access parser API (`GenericReader`). It also provides a generator API (`GenericWriter`) which consumes the same set of events. * DOM (Document Object Model) style API * Similar to [DOM](http://en.wikipedia.org/wiki/Document_Object_Model) for HTML/XML, RapidJSON can parse JSON into a DOM representation (`GenericDocument`), for easy manipulation, and finally stringify back to JSON if needed. * The DOM style API (`GenericDocument`) is actually implemented with SAX style API (`GenericReader`). SAX is faster but sometimes DOM is easier. Users can pick their choices according to scenarios. ## DOM (Document) * Support insitu parsing. * Parse JSON string values in-place at the source JSON, and then the DOM points to addresses of those strings. * Faster than convention parsing: no allocation for strings, no copy (if string does not contain escapes), cache-friendly. * Support 32-bit/64-bit signed/unsigned integer and `double` for JSON number type. * RapidJSON checks range of numerical values for conversions. ## SAX (Reader) * Support comprehensive error code if parsing failed. * Support localizable error message. ## SAX (Writer) * Support PrettyWriter for adding newlines and indentations. * Support custom precision for floating point values. ## Stream * Support `GenericStringBuffer` for storing the output JSON as string. * Support `FileReadStream`/`FileWriteStream` for input/output `FILE` object. * Support custom streams. ## Memory * Minimize memory overheads for DOM. * Each JSON value occupies exactly 16/20 bytes for most 32/64-bit machines (excluding text string). * Support fast default allocator. * A stack-based allocator (allocate sequentially, prohibit to free individual allocations, suitable for parsing). * User can provide a pre-allocated buffer. (Possible to parse a number of JSONs without any CRT allocation) * Support standard CRT(C-runtime) allocator. * Support custom allocators.